Helium radiation blistering mechanisms in tungsten: Ion channeling effects

Abstract

Understanding the radiation damage of low-energy and high-fluence helium ions on tungsten surface is of great interest and significance for developing advanced plasma-facing materials. Here, we investigate the effect of ion channeling on helium radiation blistering using a Helium Ion Microscope. 30 keV helium ions were implanted into individual tungsten grains to a fluence of 1×1018 ions/cm2 at room temperature. The grains of interest were selected based on the grayscale levels of ion channeling contrast image. It has been found that the channeling and non-channeling grains exhibit distinct blistering behaviors in both surface morphology and subsurface microstructure. In contrast with the channeling blister, the non-channeling one is smaller, shallower in irradiated bubble region, and composed of more and larger cracks beneath the surface. The underlying mechanisms were discussed based on the Molecular Dynamic simulations, which might have implications for designing and fabricating plasma-resistant materials through texture and anisotropy tailoring.